Los Angeles Unified students have just a few more days to hit the beach, ride their favorite roller coaster, chill poolside or veg out in front of the TV.

Come next Tuesday morning, they’ll be back in the classroom.

After just seven weeks of summer vacation, school will begin Aug. 14. That’s three weeks earlier than LAUSD’s traditional post-Labor Day start, although classes will also end two weeks early, finishing up on May 31.

That’s because Los Angeles Unified is implementing the so-called early-start calendar, which was tested last year on 18 campuses, most of them in the San Fernando Valley.

“This calendar lets students finish first semester at winter break,” giving them a three-week vacation that previously was filled with reading or projects, said Cleveland High Principal Herman Clay, a veteran – and a fan – of the early-start schedule.

“Parents tell us their kids were happy because they don’t have to study over that time.”

Starting school before Labor Day has long been popular in other parts of the country and is becoming more common in Southern California. Burbank Unified is starting next Monday, for instance, while Glendale Unified begins on Aug. 20. Simi Valley and Las Virgenes Unified open Aug. 22.

And most of Los Angeles’ charter schools are also starting next week.

That’s why discount and department stores began erecting back-to-school displays in early July, and why parents are flocking to snap up the must-have notebooks and backpacks, denim and sneakers.

The National Retail Federation said parents of kids in K-12 will spend an average of $688 this year on back-to-school paraphernalia, compared with $603 in 2011.

“This is one of the busiest times of the year, and it really started to pick up during the last half of the week,” said Brian Hardy, who manages the Target store in Woodland Hills.

A recent weekday found moms and dads loading their carts with brightly colored binders, pencils, notecards and lunch totes.

Graham Leibowitz had a list of school supplies on his iPad, while Diana Zamir and Revi Val simply bought what they thought their kids would like.

“I’m looking for the basics, and things can get pricey,” said mom Barbara Drescher of Woodland Hills. “I shop the back-to-school sales, and figure I’m ahead of the game.”

Stacy Mendelsohn of Calabasas took a long-term view as she shopped for her 11- and 16-year-old boys.

“There’s a lot of variety by shopping early, and sometimes they’ll need stuff at the end of the year when it’s harder to find,” she said.

LAUSD’s plans for the early-start calendar have been in the works since late 2010, when officials announced the schedule would take effect the following school year. Parents’ complaints that the calendar would disrupt family vacations and summer camp won them a one-year reprieve.

Last year, Superintendent John Deasy sought another delay because of the $1 million cost of implementing the plan. School board members decided in October to push ahead, saying the instructional benefits would outweigh any financial concerns.

That gave officials 10 months to notify students and get services in place – including buses and cafeteria meals – for the first day of school.

The shortened summer vacation did force the district’s custodial staff to look for efficiencies, said Roger Finstad, who oversees LAUSD’s Maintenance and Operations Bureau. That means the floors of thousands of classroom were simply mopped and polished – rather than stripped and re-waxed – as they have been during past summers.

“The floors won’t look as good, but they’ll be cleaned and buffed to give them that shine,” he said.

Finstad also plans to have his crews working this week – many on overtime – to make sure that schools’ air-conditioning systems are in good working order.

Hot summer temperatures – especially in hot pockets of the Valley – were among the concerns voiced when the early-start calendar was approved.

Officials note, however, the district has a 10-page policy for dealing with excessive heat, such as making water available, adjusting programs to take advantage of cool mornings and holding p.e. classes indoors.

That policy is likely to come into play next week, when the National Weather Service predicts afternoon highs will hit the 90s and will hover around 100 degrees in Valley.

“Be prepared for the warmth,” said meteorologist Ryan Kittell. “It’s going to be toasty.”